Currently, liquid crystal displays (LCD) are one of the most widely used flat panel displays. In general, a liquid crystal display has a liquid crystal layer encapsulated between a thin film transistor array substrate and a color filter substrate. When an electric field is applied to electrodes on the array substrate and the color filter substrate, liquid crystal molecules of the liquid crystal layer encapsulated between the substrates are rearranged, thereby displaying an image. The liquid crystal display includes a polarizing film (polarizing plate) outside the array substrate and the color filter substrate. The polarizing film can control polarization of light by allowing selective transmission of light traveling in a certain direction among light emitted from a backlight unit and having passed through the liquid crystal layer. The polarizing plate generally includes a polarizer capable of polarizing light in a certain direction, a protective layer, and a compensation film.
Liquid crystal displays have a fundamental problem of a viewing angle due to anisotropy of an index of refraction of liquid crystals. To improve the viewing angle of existing twisted nematic mode, wide viewing angle technologies such as vertical alignment mode, horizontal alignment mode (IPS, FFS) and the like have been employed.
Horizontal alignment mode liquid crystals have a disadvantage of slow response rate but provide a good contrast ratio and a good viewing angle at tilt angles. On the contrary, vertical alignment mode liquid crystals provide a rapid response rate and an excellent front contrast ratio. However, the vertical alignment mode liquid crystals exhibit low viewing angle characteristics due to severe fluctuation of a polarized state at tilt angles. Therefore, it is very important for liquid crystal displays employing the vertical alignment mode liquid crystals to improve the viewing angle characteristics, and a compensation film for improving the viewing angle is essential for the liquid crystal displays employing the vertical alignment mode liquid crystals.
In conventional liquid crystal displays employing the vertical alignment mode liquid crystals, the slow axis is managed by biaxial elongation. However, when the slow axis is managed by biaxial elongation, the slow axis must be set in a width direction, which necessitates separate elongation in a transverse direction, thereby making it difficult to manage the axis and increasing manufacturing costs.